NAME

       Tangram::Type::Hash::Scalar - map Perl hash of scalar keys and values

SYNOPSIS

          use Tangram::Core;
          use Tangram::Type::Hash::Scalar; # always

          $schema = Tangram::Schema->new(
             classes => { NaturalPerson => { fields => {

             flat_hash =>
             {
                opinions =>
                {
                   table => 'NP_ops',
                   key_sql => 'VARCHAR(10)',
                   type => 'int',
                   sql => 'NUMERIC(1)',
                },

                lucky_numbers => 'int', # use defaults
             }

DESCRIPTION

       Maps references to a Perl hash. The persistent fields are grouped in a hash under the
       "flat_hash" key in the field hash.

       The hash may contain as keys and values only 'simple' scalars like integers, strings or
       real numbers. It may not contain references. For hashs of objects, see
       Tangram::Type::Hash::FromMany and Tangram::Type::Hash::FromOne.

       Tangram uses a table to save the state of the collection. The table has three columns,
       which contain

       •   the id of the container object

       •   the key of the element in the hash

       •   the value of the element

       The field names are passed in a hash that associates a field name with a field descriptor.
       The field descriptor may be either a hash or a string. The hash uses the following fields:

       •   key_type

       •   key_sql

       •   type

       •   sql

       •   table

       The optional fields "key_type" and "type" specify the key and value types of the hash. If
       the type is "string" Tangram quotes the values as they are passed to the database. Not
       specifying a "type" is exactly equivalent to specifying "string".

       Optional field "table" sets the name of the table that contains the elements. This
       defaults to 'C_F', where C is the class of the containing object and F is the field name.

       The optional fields "key_sql" and "sql" specify the type that deploy() (see
       Tangram::Deploy) should use for the column containing the key and value of the hash. If
       this field is not present, the SQL type is derived from the "type" field: if "type" is
       "string" (or is absent) VARCHAR(255) is used; otherwise, the "type" field is interpreted
       as a SQL type.

       If the descriptor is a string, it is interpreted as the value of the "type" field and all
       the other fields take the default value.

AUTHOR

       This mapping was contributed by Gabor Herr <herr@iti.informatik.tu-darmstadt.de>